The first migrants to arrive in the UK after crossing the English Channel have been detained under the new “one in, one out” deal.

The detentions came as people arrived in Dover on Wednesday, the first day the pilot scheme came into force.

Pictures showed the migrants wearing life jackets disembarking from Border Force boats.

The Home Office said those detained on Wednesday afternoon will be held in immigration removal centres until they are returned to France.

Home Secretary Yvette Cooper said: “Yesterday, under the terms of this ground-breaking new treaty, the first group of people to cross the Channel were detained after their arrival at Western Jet Foil and will now be held in detention until they can be returned to France.

“That sends a message to every migrant currently thinking of paying organised crime gangs to go to the UK that they will be risking their lives and throwing away their money if they get into a small boat.”

The pilot scheme is set to last 11 months and will see the UK accepting an equal number of asylum seekers who have not tried to cross and can pass security and eligibility checks.

UK officials aim to make referrals for returns to France within three days of a migrant’s arrival by small boat, with French authorities responding within 14 days.

This is in exchange for an approved asylum seeker in France to be brought to the UK under a safe route.

Adults and families in France are able to express an interest in coming to the UK through an online platform set up by the Home Office.

They must meet suitability criteria, go through a standard visa application process and pass security checks.

If accepted, they would be given three months in the UK to claim asylum or apply for a visa, and would be subject to the same rules for all asylum seekers not allowed to work, study or have access to benefits.

The Home Office is expected to launch a campaign in coming days to make migrants in northern France and elsewhere aware of the new treaty.

As of 30 July, more than 25,000 people had crossed the Channel in small boats in 2025 – about 49% higher than at the same point in 2024.

UK and international law prevents the government from sending asylum seekers back to their country of origin before their claim has been considered and turned down. However, they can be sent to safe countries prepared to consider their claim.